Absorbent composite, an absorbent article employing the same, and methods, systems, and apparatus for making the absorbent composite and/or article

ABSTRACT

An absorbent core composite is disclosed for incorporation into a disposable absorbent article. The composite includes a first material layer and a second material layer (preferably nonwoven) partially secured to the first material layer to define at least one pocket therebetween. Preferably, multiple pockets are defined, except in the case of where a generally uniform layer or bed of absorbent is preferred or better suited for the application. The pocket is said have a fixed initial volume. Further, an aggregate of absorbent particles is provided in the pocket(s) to occupy a portion of the fixed initial volume. The absorbent particles are preferably SAP particles and is characterized by a dry volume associated with a dry state and a swell volume associated with a liquid saturation state. In respect to or for the pocket, the aggregate is characterized by a collective dry volume and a collective swell volume, wherein the pocket has an initial configuration that retains the aggregate therein.

The present application is a Continuation application of U.S.application Ser. No. 14/321,773 filed on Jul. 1, 2014 (now allowed),which claims the benefit of U.S. Provisional Application Ser. No.61/842,961 filed on Jul. 3, 2013 (expired) and U.S. ProvisionalApplication No. 61/843,986 filed on Jul. 9, 2013 (expired). Each ofthese disclosures is hereby incorporated by reference for all purposesand made a part of the present disclosure.

The present disclosure relates generally to an absorbent core compositeand disposable absorbent garment incorporating the core composite. Thedisclosure also relates to a system, apparatus, and a method of makingthe absorbent composite or the disposable absorbent article. Suchdisposable absorbent articles include diapers, training pants, adultincontinence products, bodily exudates absorbing products, fCemininehygiene products, and other absorbent products (collectively “disposableabsorbent articles”).

Prior disposable absorbent articles typically employ three basicstructural elements: a topsheet that forms the inner surface, abacksheet that forms the outer surface, and an absorbent core that isinterposed between the topsheet and the backsheet. The topsheet isdesigned to allow liquid to pass from outside the absorbent articlethrough the topsheet and into the absorbent core. The topsheet may bemade out of a range of liquid and vapor permeable hydrophilic orhydrophobic materials.

The backsheet is designed to prevent fluid from passing from theabsorbent core through the backsheet and out of the absorbent article.The backsheet may be made out of an impermeable film that extends thefull width of the article or a combination of cloth-like material andimpermeable film. The backsheet may also have vapor transmissionproperties (“breathability”) that allow vapor to pass through thebacksheet without releasing fluid stored in the absorbent core. Thebacksheet may also be made from a liquid impermeable but vaportransmittable non-woven material such as spunbond, melt-blow, spun-bond(“SMS”); spun-bond, melt-blown, melt-blown, spun-bond (“SMMS”); micro,nano, or splitable fibers; spun melt or spun laced; carded; and thelike.

The absorbent core is designed to contain and distribute fluid thatpasses through the topsheet. A typical absorbent core is made out of ahigh or super absorbent polymer (SAP) stabilized by an absorbent matrix.SAP is commonly made out of materials such as polyvinyl alcohol,polyacrylates, various grafted starches, and cross-linked sodiumpolyacrylate. SAP can be in the form of particles, fibers, foams, web,spheres, agglomerates of regular or irregular shapes, and film. Theabsorbent matrix is typically a de-fiberized wood pulp or similarmaterial. The absorbent matrix is very bulky relative to the topsheet,backsheet, and SAP. Most of a diaper's thickness comes from theabsorbent core.

Increasingly, consumers of absorbent articles are demanding thinnerabsorbent articles. To meet these demands, manufactures are decreasingthe thickness of absorbent articles by decreasing the amount ofabsorbent matrix used in absorbent cores. Although the resultingabsorbent cores are thinner, they suffer in performance. As the amountof absorbent matrix is reduced, it is less effective in stabilizing theSAP—preventing the SAP from migrating within the absorbent core. As SAPmigrates within the core, the absorbent core loses its effectiveness andno longer has uniform absorbency. For example, SAP that is not containedtends to bunch up in wetted areas and is inefficient for handlingsubsequent discharges.

Manufacturers have attempted to solve this problem by creating small,individual SAP pockets or by gluing the SAP. These solutions, however,have been largely unsuccessful. The SAP pockets merely limit themigration to movement within the pockets. However, because there isstill a movement of the particles, the absorbent core does not exhibituniform absorbency. Gluing the SAP stabilizes the SAP, but results in anuncomfortably stiff absorbent core and a loss in the SAP's swellingcapacity.

Securing the SAP by adhesive, cover layer, or other manner can alsoaffect the performance of the SAP during product use. In some instances,SAP and product performance are sacrificed for core stability and easeof manufacture. Because the absorbent core is pressed against the user'sskin during article use, the wearer is very sensitive to the touch andfeel of the core. Thus, the introduction of even a minor physicalfeature in an absorbent core design can have a great impact on thecomfort of the user.

There is a continuing need for an improved absorbent product featuringreduced composite thickness, but maintaining or improving fluid handlingproperties and sure fit and comfort. The specifications of U.S. Pat. No.8,148,598 and International Application PCT/US2014/030051 (the '051application), each of which is commonly assigned and designates at leastone common inventor as the present application, describes a priorimprovement to the state of the art and serves as background to thepresent disclosure. The disclosures both documents are herebyincorporated by reference, in its entirety, for all purposes and made apart of the present disclosure. The present disclosure may, in onerespect, be regarded as continuing and furthering the effort to provideimproved absorbent products and systems, apparatus, and methods ofmanufacturing.

BRIEF SUMMARY

The present disclosure relates generally to an absorbent core compositeand disposable absorbent garment incorporating the absorbent composite.The disclosure also relates to a system, apparatus, and a method ofmaking the absorbent composite or the disposable absorbent article. Inone aspect, improved absorbent core composites are provided withadvantageous swell capacities or void volumes. In another aspect,absorbent core composites (and methods and systems of making same) areprovided with void volume increase mechanisms, configurations, orstructures. Such functionalities are preferably triggered or activatedduring use, prior use, or during manufacture. In yet another aspect,absorbent core composites are provided with improved liquid receipt,retention, and distribution functionalities, as well asmanufacturability.

In one aspect, an absorbent core composite is disclosed forincorporation into a disposable absorbent article. The absorbent corecomposite include a first material layer (preferably nonwoven) and asecond material layer (preferably nonwoven) at least partially secured(e.g., by bond sites, bond points, adhesive, and the like) to the firstmaterial layer to define at least one pocket therebetween. Preferably,multiple pockets are defined, except in the case of where a generallyuniform layer or bed of absorbent is preferred or better suited for theapplication. The pocket is said have a fixed initial volume (e.g., asdefined by its physical configuration). Further, an aggregate ofabsorbent particles is provided in the pocket(s) to occupy a portion ofthe fixed initial volume. The absorbent particles are preferably SAPparticles and is characterized by a dry volume associated with a drystate and a swell volume associated with a liquid saturation state. Inrespect to or for the pocket, the aggregate is characterized by acollective dry volume and a collective swell volume, wherein the pockethas an initial configuration that retains the aggregate therein.

In another aspect, an absorbent core composite is disclosed forincorporation into a disposable absorbent article. The absorbent corecomposite has a first material layer, a second material layer at leastpartially secured to the first material layer to define a plurality ofpockets, each of the pockets having a fixed initial volume, andabsorbent particles provided in aggregates each disposed in one of thepockets. The absorbent particles are characterized by a dry volumeassociated with a dry state and swell volume associated with a liquidsaturation state, and wherein, for each pocket, the aggregate ischaracterized by a collective dry volume and a collective swell volume,the collective swell volume being greater than the initial pocketvolume. Each pocket is expandable from an initial configurationpartially defining the initial volume toward an expanded configurationunder which an increased pocket volume accommodates the collective swellvolume. For each pocket, the first material layer has a pressuresensitive configuration, such that pressure generated by the aggregatetransforming into the collective swell volume initiates expansion of thefirst material layer from an initial configuration partially definingthe initial volume toward an expanded configuration under which anincreased pocket volume accommodates the collective swell volume.

In another aspect, a disposable absorbent article (e.g., a diaper,training pants, adult incontinence articles, and the like) is disclosedhaving a chassis body defined by a first end margin and a second endmargin longitudinally spaced from the first end margin. The end marginspartially define front and back waist regions that are positioned abouta waist of a user during wear of the absorbent article. The articlefurther includes a topsheet, a backsheet, and an absorbent corecomposite disposed between the topsheet and backsheet. The compositeincludes a first nonwoven layer, a second nonwoven layer at leastpartially secured to the first nonwoven layer to define a plurality ofpockets therebetween, the pockets having a fixed initial volume, and anaggregate of SAP particles disposed in the pocket to occupy a portion ofthe fixed initial volume. The SAP particles are characterized by a dryvolume associated with a dry state and a swell volume associated with aliquid saturation state, and wherein, for the pocket, the aggregate ischaracterized by a collective dry volume and a collective swell volume,wherein the pocket has an initial configuration that retains theaggregate. Further, an outside surface of the first nonwoven layerexhibits surface discontinuities in the initial configuration of thepocket. The outside surface is extendible, however, to substantiallyremove the discontinuities and place the pocket in an expandedconfiguration defining an increased pocket volume. The discontinuitiesmay be corrugations, folds, pleats, and other (temporary) deformationsthat are removable upon extension of the outside surface.

In another absorbent core composite for incorporation into a disposableabsorbent article, the absorbent core composite has a first materiallayer having an outside surface forming a bodyside outer surface of theabsorbent core composite, a second material layer having an outsidesurface forming an opposite outer surface of said absorbent corecomposite, a first layer of absorbent particles disposed between theouter surfaces of the absorbent composite and having an average sizedimension (i.e., the average width or diameter of the particles), and asecond layer of absorbent particles disposed between the outer surfacesof the absorbent composite and having an average size dimension lessthan the average size dimension of the first layer. The first layer ofparticles are situated substantially in the first material layer and thesecond layer of particles are situated substantially in the secondmaterial layer. In a further embodiment, an intermediate layer isdisposed between the first and second material layers and containsanother layer of absorbent particles. The densities of the two or threelayers may be selected to achieve a desired gradient of absorbentparticles (and absorbent properties).

In another aspect, a method is disclosed for forming an absorbentcomposite for incorporation into a disposable absorbent article. Themethod entails providing a first material layer, positioning a secondmaterial layer beneath the second material layer, providing a supply ofabsorbent particles composed of a population of a first absorbentparticles having a first average size dimension and a second populationof absorbent particles having a second average size dimension less thanthe first average size dimension, and depositing the first and secondpopulations of absorbent particles onto the first material layer suchthat absorbent particles of the first population are maintained in thefirst material layer and absorbent particles of the second populationfilter through the first material layer and settle in the secondmaterial layer. The first material layer may be a low density nonwovenhaving a density between 0.01 to 0.03 g/cc and the second material layermay be of a higher density nonwoven.

In another aspect, another absorbent core composite is disclosed forincorporation into a disposable absorbent article. The absorbent corecomposite includes a bodyside first material layer (nonwoven), and asecond material layer (nonwoven), wherein the first and second materiallayers define a space therebetween. The defined space contains a layerof superabsorbent particles, which includes a population of SAPparticles and a population of non-SAP spacing particles that are smallerthan the SAP particles and generally positioned between two or more SAPparticles, thereby spacing two or more SAP particles from one another.Further, the spacing particles may be selected from the group of spacingparticles consisting of: inert particles; water-soluble particles;volatile particles; ion-exchange particles; and combinations thereof.

In another aspect, another disposable absorbent article is disclosedhaving a chassis body defined by a first end margin and a second endmargin longitudinally spaced from the first end margin, the end marginspartially defining front and back waist regions that are positionedabout a waist of a user during wear of the absorbent article. Thearticle further includes a topsheet, a backsheet, and an absorbentcomposite disposed between the topsheet and backsheet. The absorbentcomposite includes a first material layer having an outside surface, asecond material layer having an outside surface, a first layer ofabsorbent particles provided between the outside surfaces, and a secondlayer of absorbent particles provided between the outside surfaces,wherein the second layer of absorbent particles has absorbent propertiesdifferent from said first layer.

A method is also disclosed for making an absorbent composite forincorporation into a disposable absorbent garment. The method entailsconveying a first sheet of a first nonwoven layer, depositing absorbentparticles on the first sheet, and applying a second sheet of a secondnonwoven layer over the deposited absorbent particles and first sheet,thereby forming a composite including two material layers sandwichingabsorbent particles therebetween. The method also provides bonding thefirst and second material layers to secure, at least partially,absorbent particles therebetween. In one embodiment, prior to conveyingthe first sheet, a surface of the first sheet is deformed to formlaterally elongatable surface discontinuities.

The disclosure also provides for systems and methods for making thearticles and composites discussed above or in the Detail Description, orillustrated in the Figures. It should also be noted that variousembodiments are disclosed herein. Some embodiments feature elements(design features, steps or components) that are not described as beingspecifically incorporated into other embodiments. Many more variationsor embodiments are contemplated, however, and such further combinationsor incorporation of elements will be evident to one skilled in the artin possession of the present disclosure.

Lastly, the absorbent composite features means for altering the initialpocket configuration during use (e.g., in the event if liquid intake bythe absorbent article) to accommodate the swell volume of the aggregate.For example, the altering means may be provided by the pocket beingexpandable from the initial configuration defining the initial volumetoward an expanded configuration under which an increased pocket volumeaccommodates the collective swell volume, the collective swell volumebeing greater than the collective dry volume. Further, such means foraltering the initial pocket configuration means at least one of thefirst and second material layers being elongatable in response toswelling of SAP aggregate in said pocket. The subject elongatablematerial layer may be corrugated or may have a plurality of foldstherein extending in the longitudinal direction. The altering means mayalso be provided by a breakable substrate such as tissue, dry-crepetissue or a slitted substrate (weakened material). The altering meansmay, in the alternative, be provided by breakable bonds, such asbreakable bond point or water-soluble adhesive, that otherwise securethe material layers to define the pocket(s) and contain the SAPaggregate (i.e., during SAP swell).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a disposable absorbent articleincorporating an absorbent composite according to the presentdisclosure;

FIG. 1B is a top plan view of the disposable absorbent article in FIG.1A, in a flat and extended position;

FIG. 1C is an exploded view of the disposable absorbent article in FIG.1A;

FIG. 1D is a schematic of a system for making an absorbent composite;

FIGS. 2A-2B is a simplified illustration of an absorbent core compositewith a plurality of pockets of aggregates of absorbent particles;

FIGS. 2C-2E are bonding patterns suitable for forming pockets in theabsorbent core composite such as those in FIGS. 2A-2B;

FIG. 3A is an elevated cross-sectional view of a section of an absorbentcomposite having an elongatable substrate partially defining a pocketSAP aggregate, according to the present disclosure, the pocket shownfirst in a pre-activated and in a fixed initial configuration and then,activated an in an expanded configuration;

FIG. 3B is a perspective view of a sheet of the absorbent composite inFIG. 3A;

FIG. 3C is an elevated cross-sectional view of a section of analternative absorbent core composite having an elongatable substrate,according to the present disclosure, shown in a pre-activated state;

FIG. 3D is an elevated cross-sectional view of the section of analternative absorbent core composite in FIG. 3C, shown in an activatedor expanded state;

FIG. 3E is an elevated cross-sectional view of a section of a diaperincorporating the absorbent composite in FIG. 3C;

FIG. 4 are simplified illustrations of portions of a process of rifflingor corrugating a non-woven sheet for incorporation into a absorbentcomposite, and equipment suitable for use in the process;

FIG. 5 are simplified illustrations of an absorbent core compositehaving an elongatable substrate according to the present disclosure;

FIGS. 6A-6C are simplified illustrations of multi-layer absorbent corecomposites, according to the present disclosure;

FIGS. 7A-7B are simplified illustrations of folded absorbent corecomposites according to the present disclosure;

FIGS. 8A-8C are simplified illustrations in plan view of absorbent corecomposites featuring cross-directional profiling of absorbentproperties, according to the present disclosure;

FIGS. 9A-9C are simplified diagrams illustrating the relation betweentravel of liquid on an absorbent core and changes in absorbent propertyof the SAP in areas along said liquid travel;

FIG. 9D is graph showing the relation between SAP absorbent capacity andtarget liquid ionic strength;

FIG. 10A-10B is a depiction of a bar chart displaying suitable SAPparticle size distribution;

FIG. 10C is a depiction of a bar chart displaying suitable hotmeltparticle size distribution;

FIG. 11 is a simplified illustration of an absorbent compositeexhibiting layered particle size filtration on nonwoven layer;

FIG. 12 is a simplified illustration of a SAP aggregate with and withoutinert particle spacers;

FIG. 13 is graphical chart of simplified illustrations of SAP aggregateconstitutions during bonding and product use;

FIG. 14 is a simplified illustration of a system and process for makingan absorbent composite sheet having lanes of SAP, according to oneembodiment;

FIG. 15 is a simplified illustration of a system and process of makingan absorbent composite sheet utilizing hotmelt fibers in the compositeaccording to one embodiment;

FIG. 16 is schematic illustrating a system and process for making anabsorbent composite according to various embodiment; and

FIG. 17 is a schematic illustrating a system and process for making anabsorbent composite according to various embodiments.

DETAILED DESCRIPTION

Referring first to FIG. 1A, a disposable absorbent article is shown inthe form of a diaper 10. The diaper 10 is a type of absorbent articlethat readily incorporates, as its central functional component, anabsorbent core composite according to the present disclosure. The basiccomponents of the diaper 10 are a topsheet 50, a backsheet 60, and anabsorbent core 46 (not shown in FIG. 1A but in FIGS. 1B and 1C) disposedbetween the backsheet 60 and topsheet 50. The diaper 10 also featuresupstanding barrier cuffs 34 that extend longitudinally along the diaperand are elasticized to conform to the buttocks of the wearer.Additionally, the diaper includes an elastic waist band 52 and fasteningelements 26. Element 26, is extendible to and engages the correspondingopposing end of the diaper 10 to secure the diaper 10 about the wearer.

FIG. 1B illustrates a composite web structure of the diaper 10 in agenerally flat and unfolded configuration. As will be explained below,the web structure may be subsequently trimmed, folded, sealed, weldedand/or otherwise manipulated to form a disposable diaper 10 in afinished or final form. To facilitate description of the diaper 10, thedescription refers to a longitudinally extending axis AA, a laterallyextending central axis BB, a pair of longitudinally extending side edges90, and a pair of end edges 92 that extend between side edges 90. Theimaginary lines AA and BB shown are also referred to as the diaper'slongitudinal and lateral centerlines, respectively. Generally, whendiscussing the positions or orientations of various elements of thediaper 10, references made to lateral and longitudinal directions orextensions relate or correspond with the axes AA and BB (unlessreferring specifically to the context of that particular element). Itshould also be noted that the direction of the longitudinal centerlineAA generally corresponds with the machine direction (MD) of the diaper10 while the direction of the lateral centerline BB corresponds with thecross machine direction (CD) of the diaper. The machine direction (MD)of a diaper element such as a topsheet or backsheet, and other nonwovenswhich contain fibrous elements, can be determined by observing thealignment and/or condition of the fibers in the diaper element. Thefibers normally align with the machine direction. This can be observed,for example, under a microscope long after the diaper has beenmanufactured.

Along the longitudinal axis AA, the diaper 10 includes a first endregion or front waist region 12, a second end region or back waistregion 14, and a crotch region 16 disposed therebetween. Each of thefront and back waist regions 12, 14 is characterized by a pair of earregions or ears 18, which are located on either side of a central bodyportion 20 and extend laterally from the side edges 90. A fasteningstructure 26 (e.g., a conventional tape fastener) is affixed to each ofthe ears 18 along the back waist region 14 of diaper 10. When the diaper10 is worn about the waist, the front waist region 12 is fitted adjacentthe front waist area of the wearer, the back waist region 14 is fittedadjacent the back waist area, and the crotch region 16 fits about andunderneath the crotch area. To properly secure the diaper 10 to thewearer, the ears 18 of the back waist region 14 are brought around thewaist of the wearer and toward the front and into alignment with theears 18 of the front waist region 12.

FIG. 1B reveals an absorbent core 46 disposed beneath the topsheet 48and an acquisition and distribution layer (ADL) 48. FIG. 1C is anexploded view of the diaper of FIGS. 1A and 1B, and illustrates, insimplified form, the absorbent core 46 as a multi-component laminatehaving a generally rectangular shape. In other preferred embodiments,the absorbent core 46 takes on an hourglass shape featuring a laterallynarrowed central region. The absorbent core 46 is generally composed ofa top nonwoven layer 70, a bottom nonwoven layer 72, and a layer, body,or collection of absorbent materials 74 therebetween. Prior toincorporation into the diaper, the absorbent core body 46 is oftenreferred to as an absorbent composite or absorbent core composite. Agenerally planar extension of the absorbent composite may be presentedand referred to as a web or an absorbent composite sheet duringmanufacturing and as a product or article of manufacture. The presentdisclosure is primarily directed to an improved absorbent compositeconstruction and systems and methods of making the composite or anabsorbent composite sheet from which absorbent composite is sourced. Thepresent disclosure is also directed to a disposable absorbent article inwhich the absorbent composite is incorporated as the absorbent core.

An absorbent core composite of the type addressed by certain embodimentsof the present disclosure features pockets or containers in which SAP isretained. Other improved absorbent core composites are described whichalso exhibit improved fluid handling performance and are amendable tothin-core constructions, but may not necessarily feature or requirepockets. Without pockets, these composites can be made with a generallyuniform profile and depth.

FIG. 1D is taken from the '598 patent and reproduced herein, in mostpart, to illustrate suitable processes, subprocesses, systems, andcomponents for making the absorbent composite and/or a disposableabsorbent article incorporating the composite. Certain embodiments ofthe absorbent composite described herein may require modifications tothe method and system illustrated by FIG. 1D. Description providedherein and/or the general knowledge in the industry will make therequired modification fairly evident, however, to those skilled in therelevant manufacturing art.

Referring to FIG. 1D, a fabric 125 is dispensed from roll 120 andcarried along a production line on a conveyer belt 100. The fabric 125is a thermo plastic material that may be a woven, nonwoven, film, or acombination thereof. In some embodiments, the fabric 125 is secured tothe conveyor belt 100 by a vacuum system 110. The vacuum system 110serves to conform the fabric 125 to the convey belt 100. SAP particles135 are then deposited on the fabric 125 by a SAP dispenser 130. The SAPdispenser 130 may be configured to position SAP particles in theirdesired position or lanes on the first fabric or may be configuredmerely to deposit SAP particles on the first fabric, whereon the SAPparticles are positioned by another means. Once SAP particles have beendeposited and positioned on fabric 125, a second fabric 155 introducedinto the production line from roll 150 is moved into engagement with theSAP fabric 125 web. The second fabric 155 may be selected from a varietyof materials including spun-bonded thermoplastic or similar woven ornonwoven material, film, or combinations thereof.

In FIG. 1D, a thermal bonding system is shown including calendar rolls160 and 170 which are used to engage and bond fabrics 125 and 155together. Other bonding systems may be suitable or preferred dependingon the application, however. For example, an ultrasonic bonding systemmay be used in place of the calendar rolls to provide bond points inmany applications. The bond pattern may be aligned with the distributionof the SAP particles 135. Once the fabrics are bonded to form a sheet orlaminate of absorbent core composite, the sheet may be gathered into aroll 200. In other applications, depending on the composite application,the laminate may be advanced for further processing, including slitting,application of additional layers, incorporation with or into anotherproduct or even into a disposable absorbent article.

In one embodiment, the core composite has a top preferably nonwovenlayer (fabric) and a bottom, preferably, nonwoven layer (fabric). Thetwo layers may be bonded or otherwise engaged to form the pockets, asdescribed in U.S. Pat. No. 8,148,598 B2 issued on Apr. 3, 2012, andInternational Application PCT/US2014/030051, both of which are commonlyassigned. The '598 patent further describes a core constructionemploying such pockets, which is particularly suited for containing theSAP and readily and effectively disposing SAP material or SAP particlesto perform the liquid absorbing or retention function, and preferably,in some embodiments, without the inclusion and employment of anabsorbent matrix. In these further embodiments, the absorbent compositeis characterized as being free (or lacking) of an absorbent matrixcapable of stabilizing an absorbent layer of particles against particlemigration and alternatively, as being pulpless. InternationalApplication PCT/US2014/030051 (the '051 application) teach furtherabsorbent composite constructions and methods of manufacturing thatadvantageously secure absorbent materials beneath a cover layer, whilealso enhancing the fluid handling performance of the absorbent materialsand\or maintaining user comfort. Accordingly, the ‘disclosure of the'598 patent and the '051 application may serve as starting points andbackground for the core composite constructions, absorbent articles, andmanufacturing processes, and apparatus introduced herein. The '598patent and the '051 application are hereby incorporated by reference inits entirety, and for all purposes including serving as background andreference to facilitate understanding and implementation of theproducts, systems, apparatus, and methods described herein.

Absorbent core composites such as that depicted in FIGS. 2A and 2B maybe made with particularly advantageous arrangements of aggregates ofabsorbent particles, such as the SAP particles. Each of the aggregateson the absorbent composite 510 is represented by the diamond-shapedenclosure 514 in the pattern. In preferred embodiments, SAP is employedas the absorbent particles in the aggregates. Furthermore, SAPaggregates in each of FIG. 1 are preferably maintained in place andstabilized by physical entrapments or containers provided by theengagement of a first fabric disposed generally above the SAP aggregatewith a second fabric disposed generally beneath the SAP aggregate. Thus,in an alternative view, the diamond units represent the outline of thecontainers or pockets, reflecting in particular embodiments, theengagement of the top fabric with the bottom fabric, as previouslydescribed herein. The containers or pockets are also referred to ascells, herein.

The absorbent performance of the SAP can be affected by the size andstructure of the container. As SAP becomes more saturated, itspermeability is reduced. Water cannot pass through the SAP particle dueto the high level of water already contained within the SAP particle andeventually the SAP can completely halt the passage of further fluidthrough it. This is known as gel blocking. Also, as SAP becomes moresaturated, it swells and its volume increases. By confining the SAP in asmall container of fixed volume it is possible to restrict the swellingof the SAP and prevent it from reaching its highest saturation levels(and by consequence stop the SAP from reaching its lowest levels ofpermeability). The degree to which the SAP particle is restricteddepends on a number of factors, including: the nature and size of thecontainer, the size and frequency of any breaks in the container (e.g.,along the side walls), the amount of SAP disposed in the container, andthe amount of fluid absorbed by the SAP. Further, the performanceproperties of SAP are affected by its degree of saturation.Specifically, absorbent composite properties such as permeability,absorption rate, capillary pressure (arising from the void space in thecomposite) will vary significantly as the SAP changes from dry to fullysaturated. In accordance with a method of the present disclosure, targetor optimal performance of the SAP may be achieved by changing the sizeof the container and/or the SAP concentration so as to physicallyconstrain the swelling of the SAP and limit the maximum saturation pointof the SAP. By incorporating these physical features, preferred levelsof permeability or a preferred absorption property may be achieved intarget regions of the absorbent core. Thus, by playing with the twovariables of pocket size and the amount of SAP in the pocket, theminimum permeability of that container or pocket may be “set”. Pocketsin some regions of the diaper may be prevented from gel blocking and thepermeability of that region of the core may be optimized. A gradient ofpocket size may also be established to obtain maximum flow andutilization of the absorbent core. This gradient will extend from thetarget zone to the ends or sides of the diaper.

The various arrangements of containers or pockets also promote SAP andcore utilization and prevent fluid from bypassing the containers.Ideally, fluid should leak or flow from container to container as theSAP reaches the maximum level of saturation which is set either by theproperties of the SAP or the volume of the pocket into which it isexpanding. Applicants contemplate that, in some of the previouslydescribed composites or arrangements of pockets, there may be a tendencyfor fluid to leak between the pockets. That is the fluid runs rapidlyalong the channels formed by embossing lines and does not enter thecore. Fluid also flows through the nonwoven material, although not asrapidly as on the surface but faster than SAP to SAP and through SAP. Tomitigate this tendency, arrangements or patterns for the containers arepreferably ones that minimize or eliminate short and direct routes (asmay be established along embossing lines) of fluid flow from the corecenter to the side margins of the core. Specifically, embossing linesfor the fluid to flow along from the center of the core to the side edgeof the core. To illustrate, containers or pockets shaped as diamonds arepreferred to ones formed in squares or rectangles, because the diagonallines or channels formed by the diamond containers are longer and morecircuitous. Circles are also effective if packed in a way that does notpresent channels that flow quickly to the edge. In more preferredarrangements, fluid flow is forced to change directions one or moretimes before flowing through the side of the diaper.

An absorbent core for a baby diaper or adult incontinence product isrequired to absorb fluid quickly, in an anatomically aligned region ofthe core, absorb all the fluid without leaking at the sides or ends ofthe product and hold on to that fluid without wetting the user's skinparticularly when under pressure caused by the user's bodyweight. Thisis accomplished by providing regions of the core having differentperformance parameters defined by the size of the containers retainingthe SAP, as well as the arrangement of the containers. Thus, a core maybe designed to attain optimized performance characteristics by changingthe size of the pocket and/or the concentration of SAP within thatpocket.

In FIG. 2, large diamond shaped containers or pockets 514 of absorbentparticles aggregate 522 are present in a region anatomically alignedwith the point of insult. The containers then gradually reduce in sizetoward the sides and front and rear margins or edges of the core 510.There are three distinct regions of containers. In the crotch region“A”, large diamond shaped pockets are provided. Adjacent and surroundingthe crotch region is an intermediate region “B” of pockets of smallersize than those in the crotch region (A). Among other things, thesmaller pockets of this intermediate region (B) present breaks in thepotential fluid flow around the SAP aggregates and along embossinglines. As described previously, the presentation of such barriers todirect escape of fluid flow through the side margins prevents leakageand promote utilization of the SAP aggregates. Finally, a third region“C” of pockets is present near each of the end edges of the core 510populated by even smaller sized pockets of SAP aggregates.

FIG. 1B illustrates a second exemplary arrangements of SAP aggregates522 and pockets 514. In this example, small, diamond shaped pockets 522are disposed in the region anatomically aligned with the point of fluidinsults. The pockets then gradually increase in size in regions disposedtoward the sides and front and rear edges of the core. The twoarrangements (in FIGS. 1A and 1B) provide alternative ways ofstructuring the expected flow gradient and as well, handling of theliquid insults. The absorbent composite and arrangement of pockets inFIG. 1A may provide for a center region with a larger capacityinitially, but which, over time, will redistribute liquid in its voidvolume, or from subsequent liquid insults, to smaller adjacent pocketsor cells. With the pattern of FIG. 1B, the center region may be equippedwith smaller capacity initially, which will cause the liquid to travelto larger cells. It may also generate a surface topography that preventsleakage from the sides and ends of the diaper, i.e., “dams” will becreated that intercept and absorb surface flow.

Although the amount of SAP applied on a core by weight is of a capacitythat is theoretically sufficient to achieve a certain retention target,Applicants found through experimental observations and then,calculations, that the SAP needed more volume in the pockets.Applicants' teabag volume calculations, which are reproduced underTables A and B below, suggest that there is insufficient volume in thepockets, collectively, to allow the SAP to fully swell, hold and containthe target 750 g of liquid. There is insufficient void space within thecore to accommodate the excess volume provided by the swollen SAPpopulation. Without more expansion room, the absorbent capacity of theSAP was reduced.

The teabag calculations suggest that a diamond shaped pocket having aside dimension of 23.5 mm has a maximum internal volume of about 2.5cm³. This is supported by testing that further suggests that a 23.5×23.5mm bag containing 0.25 g of SAP absorbed around 2.5-3.0 g of salinesolution. The core has 84 pockets resulting in a total internal volumeof only 210 cm³, which is less than a third of the volume required tohold 750 g (˜746 cm³) of fluid.

TABLE A Quick Calculation of Pocket Volume for Pocket Designs For AdultProduct width mm 23.55 25 50 75 100 length mm 23.55 25 50 75 100 Volumeper pocket* mm3 2488 2977 23814 80371 190510 cm3 2.49 2.98 23.81 80.37190.51 Total core area cm2 480 480 480 480 480 mm2 48000 48000 4800048000 48000 Approx. no. of pockets 86 76 19 8 4 Total volume capacitycm3 214 226 452 643 762 Total desired retention capacity is in theregion of 750 g! *V = w³ (h/(πw) − 0.142 (1 − 10^((−h/w))))

TABLE B For Baby Diaper width mm 25 50 75 100 length mm 25 50 75 100Volume per pocket mm3 2977 23814 80371 190510 cm3 2.98 23.81 80.37190.51 Total core area cm2 400 400 400 400 mm2 4000 4000 4000 4000Approx no of pockets 64 16 7 4 Total volume capacity cm3 191 381 563 762

In one aspect, the present disclosure presents different approaches tosolving the above-illustrated capacity issues without compromisingcertain advantageous features of the core design. For example, variousembodiments are described or contemplated that employ diamond-shapedpockets in a core composite configuration but with the means orcapability to increase void volume or capacity during use events. Thepocket configuration is substantially defined by two material layers andhow these two layers are secured to one another and/or the aggregate ofabsorbent particles contained in the pocket. It is this pocketconfiguration that determine the volume of the pocket and whether it canaccommodate SAP well. In certain embodiments, the pocket configurationis not fixed but dynamic. A means or mechanism is provided for alteringthe pocket configuration so as accommodate SAP swell, particularly whenthe collective swell volume of the SAP aggregate nears or exceeds thefixed initial volume of the pocket. In some embodiments, the pocketconfiguration is altered (e.g., responsive to SAP swell (pressure orliquid contact) to increase pocket volume or capacity and/or to allowescape of liquid or SAP from the pocket.

In further embodiments, such pockets may be strategically positioned inor around certain areas of the core to effect desired fluid flow andcore absorption characteristics. In yet further embodiments, theabsorbent composite may be contained or encapsulated in a single or asmall number of pockets.

Multiple Layers of Core Material

In this embodiment, the absorbent core composite features a multi-layercore construction. By increasing the number of core layers and thus, thez-dimension of the core, the number of pockets in the absorbent core isincreased. See e.g., FIG. 3C and FIGS. 6A-6C. As a result, the totalvoid space available in the product is also increased (multiplied)(assuming total SAP content remains the same but SAP amount per pocketis reduced). FIGS. 6A-6C provides examples of multi-layered absorbentcore composites 610 a, 610 b, 610 c. The configurations for the lattertwo composites 610 b, 610 c position and favor additional core layerscentrally to coincide with target insult regions, for example.

In an alternative construction, a wider core sheet is provided and thenfolded to produce the multiple core layers. Consequently, the total voidspace available in the product is also increased (multiplied). Corelayers can be the full length of the absorbent core or any partiallength of the absorbent core and can be stacked in any configurationincluding overlapping partial lengths of core.

Increase Pocket Size Dimension

In further embodiments, the core pocket dimensions are evaluated andmanipulated to achieve increased void space. The thrust of these corepocket designs is based on the premise that a larger pocket providesgreater void space. Generally, the volume of available void spaceincreases exponentially as the side length of the pocket is increased.With this modification, a higher total capacity per core may be achievedwithout increasing the overall core size or the number of layers. Thus,in respect to the pocket configuration of FIG. 2, larger diamond shapedpockets are used, which also reduces the number of cells pocketsoverall.

Wider Core Sheet Folded to Multiple Core Layers.

Referring to FIGS. 7A-7B in one embodiment, a wide core composite 710can be made (FIG. 7A) and then folded (FIG. 7B), along one or morefolding lines FF running parallel to lateral side edges 720 of thecomposite to reduce the width of the total core composite to a narrowerwidth. Total void space is increased, as in other designs (assumingtotal SAP content is the same but SAP amount per pocket is reduced).Together, the two folded portions may provide a contiguous top layer 722to the composite. Notably, in such case the base layer effectivelyencapsulates the composite and functions as both a core layer and a baselayer. Alternatively, in a further embodiment, a longer core is foldedalong one or more folding lines parallel with the longitudinal front andrear edges of the core to reduce the length of the core to a desiredlength.

In a method for producing a suitable folded core sheet, SAP free lanesmay be provided on the sheet of the nonwoven base layer as the sheet isconveyed. For example, SAP is selectively deposited on the substratealong three longitudinally-extending lanes. Adhesive applied on thesheet and/or the SAP may be used to secure the SAP in place.Alternatively, a cover layer may be applied over the SAP. The three SAPlanes are mutually spaced apart by way of two SAP-free lanes, whichextend in parallel with the SAP lanes. Downstream in the manufacturingprocess, perhaps after a cover layer is provided over the SAP, theabsorbent composite may be readily folded laterally along a natural foldline extending through the SAP-free lanes (where the composite isthinner). Before folding, the base and cover non-woven layers may alsobe bonded along the SAP-free lanes. Notably, for a compositeconfiguration such as that depicted in FIG. 7, the base layer mayfunction both as the base layer and the top cover for the resultantabsorbent core composite.

Extendible or Elongatable Substrates

In some embodiments, structural mechanisms are employed which, whentriggered, expand or extend the dimension of one of the layeredcomponents of the core composite or more preferably, of the pocket. Withthe extension of the substrate, the pocket volume is increased,primarily in the Z-direction (vertical direction). FIGS. 3 and 5illustrate another absorbent composite (320, 520) having at least oneelongatable substrate, preferably as a nonwoven cover layer. The surfaceof the nonwoven layer is equipped with folds, flaps, pleats, grooves, orother temporary surface breaks or deformation formed during manufactureof the composite and which disturb the otherwise flat surface. Ratherthan being flat or smooth, the surface is riffled or corrugated.Observed in plan view, the surface is not continuous but exhibit linesor breaks (creped, riffled or corrugated) due to folds, protrusions,grooves or depression. The surface may be stretched, however, to smoothout the surface and remove these temporary deformations ordiscontinuities. In doing so, the surface area is increased (i.e., asurface dimension is elongated or extended). Accordingly, in onerespect, the riffles or corrugations are said to represent reserved areaor elongation of the surface. For present purposes of description, theterms creped, riffling, or corrugations are used to interchangeably tomean the appearance and condition of a surface as described above,including having the capacity to smoothen, elongate, or extend toincrease a surface area dimension.

The riffles or corrugations may extend in either the machine directionor cross direction, but preferably, in the machine direction due to easeof assembly. As the SAP swells, it applies pressure on the nonwovenlayer placing it in tension. The resulting lateral forces causes thesurface discontinuities to unfold or smooth out, as the nonwoven layerextends laterally. In this way, the volume of the pocket expands toaccommodate the swell of the SAP.

In FIGS. 3A and 3B, an absorbent core pocket P is shown having anelongatable substrate in the form of a riffled or corrugated non-wovencover layer A. FIG. 3A shows the pocket P both in a pre-activated state(left side of FIG. 3A) and then in an activated or expanded state (rightside of FIG. 3A) characterized by SAP swell. The composite includes abase non-woven layer or substrate B, the riffled or corrugated coverlayer or substrate A, and SAP aggregates 335 situated therebetween. Thesurface of the cover layer provides corrugations 330 under which the SAPis situated. The total SAP amount in the pocket may be in the range of50 gsm to 600 gsm. Defined by a series of peaks and trough, thecorrugations 330 may be fine and closely packed, or may be larger andprovide deeper troughs or valleys. The corrugations 330 may be welldefined such that the bottom of the troughs are close to the basesubstrate B, such as shown in FIG. 3A. In this configuration, thecorrugations 330 tend to compartmentalize SAP 335 into mini-pockets. Inother configurations, the bottom troughs are spaced further from thebase substrate and the SAP is largely settled below the cover layer.

As taught herein, bonding of the base nonwoven layer B and the coverlayer nonwoven A can form pocket patterns such as the diamond pocketpattern 340 (with intermitted or spaced apart bond sites) on a sheet Sof the absorbent composite 320 shown in FIG. 3B. The perimeter of thepocket forms a flat bonded area 342 as shown in FIG. 3A. A generallyflat perimeter about the pocket P is maintained during expansion of thepocket P as shown in the expanded state of the pocket in FIG. 3A. Thus,the horizontal or lateral length of the pocket P in FIG. 3A does notactually extend because the cover layer A is fixed at the bonded area342. Extension of the cover layer A is instead generally accommodated byexpansion of the pocket P in the z-direction (depth).

The corrugations 335 in the non-woven structure of the cover layer maybe pulled or tensioned to elongate the surface dimension. When triggeredby expanding or swelling SAP aggregate, the pocket transforms from arest or pre-activated configuration to an activated or expandedconfiguration. This is illustrated in the right portion of FIG. 3A. Inthe activated configuration, the nonwoven surface has expanded orelongated such that the pocket volume that it defines, at leastpartially, has increased to accommodate the collective swell volume ofthe aggregate of SAP particles. Typical or preferred elongation(extended length/original length) is greater than about 1.2. Notably,the base nonwoven substrate B remains relatively flat in thisembodiment.

In exemplary embodiments of a disposable absorbent garment 310, as shownin FIG. 3E, the pockets P of absorbent composite 320 are encased betweena backsheet 360 and a topsheet 350. The backsheet 360 and topsheet 350maybe bonded or otherwise secured, but their placement and configurationare such that these layers do not restrict elongation of the riffledsubstrate and expansion of the pockets P. Specifically, the topsheet isprovided with sufficient play and/or flexibility to readily accommodatethe elongation and expansion. In some applications, the topsheet and/orbacksheet is bonded to the absorbent core composite throughout, e.g.,employing the bonding patterns discussed above to form the pockets andalso bond the topsheet and backsheet. Such a bonding pattern mayrestrict some elongation of the riffled substrate. In otherapplications, the topsheet and\or backsheet is bonded only at theperiphery. This bonding technique would prove less restrictive on thelateral extension of the riffled substrate. In one preferred embodiment,the topsheet is bonded only at the periphery and along onelongitudinally-extending center line. In further embodiments, an ADLlayer is positioned between the topsheet and the core.

In another preferred absorbent structure as first shown in FIGS. 3C and3D, the pocket P includes a top substrate A, a bottom substrate C, and amaterial layer B intermediate the top substrate and bottom substrate.Substrates A and C are preferably non-woven layers that are riffled orcorrugated prior to absorbent core composite assembly. As shown, thesurfaces of substrates A and C exhibit riffles or corrugations 330 and apopulation of SAP material 335 is provided in each of the pocket spacesabove and below the intermediate layer B. In the pre-activated mode, thedry SAP 335 settle close together adjacent the intermediate layer B,asserting minimal pressure on substrates A and C. The pocket P remainsin a somewhat shallow or collapsed mode, exhibiting minimal height(z-direction) and riffled surfaces. FIG. 3D illustrates the pocket P andthe SAP 335 contained therein in an active or nearly saturated mode. Thespace beneath substrates A and C now contain SAP of larger sizes. TheSAP materials have absorbed liquid to near volumetric capacity, therebyexpanding mostly in the z-directions, which asserts pressure onsubstrates A and C and forces the layers to lengthen along the MD orX-direction. As a result, more void space is created to accommodate theexpanding SAP constituency.

The intermediate layer B may also be provided as an elongatablesubstrate in further designs. In preferred embodiments, substrate B isan ADL-like structure, i.e., bulky and capable of distributing fluid. Itis normally preferred, however, that one nonwoven layer of the compositeis not elongatable. Such a fixed-length nonwoven layer is required forabsorbent core composite processing and handling. Otherwise, the corecomposite would stretch as it is being made rather than maintain thereserved length until product use. So, for a preferred two-layercomposite, only one layer is corrugated. In a preferred three-layercomposite, two of the layers are typically elongatable while the middleor intermediate layer is not elongatable.

In further embodiments, the intermediate layer B is a breakablesubstrate and more specifically, breakable upon water contact. Theintermediate layer B may be provided by a tissue layer, for example. Asthe pocket P takes in liquid and the SAP expands, the wetted tissuelayer B breaks apart to allow SAP expansion to and from either top orbottom pocket compartments. The direction of SAP expansion (ormigration) may be governed by physical restriction or pressure appliedto components of the pocket, and/or the direction of liquid intake andtravel. In many instances, especially for pockets situated in or aboutthe central region of a diaper where insult is initially expected, SAPimmediately beneath the cover layer A will begin to swell first andexert pressure downward to adjacent SAP particles and then theintermediate tissue layer B.

In addition to improving the capacity of the core pockets, the riffledcore design produces a few side benefits. Due to the depth of thecorrugations, the riffled nonwoven layer necessarily provides morenonwoven material than a flat layer. The non-woven material is absorbentand thus, the additional nonwoven material and nonwoven surface areaincreases the absorbency of the composite. The increased thickness ofthe nonwoven surface due to the depth of the corrugations also improvesthe absorption rate of the composite. The nonwoven surface functions astemporary storage for liquid much like a typical acquisition anddistribution layer.

As compared to a plain core surface, the appearance of the corrugatedstructure, perhaps in combination with a desirable pocket pattern, maylook aesthetically pleasing and technologically advanced (marketappeal). It may also look more comfortable, which, indeed, is a sidebenefit of the design. The corrugated core structure should be lessstiff and generally softer than traditional core designs. A diaper (orother articles) employing the absorbent core is, therefore, morecomfortable to a user than a traditional diaper.

In preferred embodiments, the riffled nonwoven layer is configured suchthat the core is stretchable in the CD (cross) direction. See FIG. 3C.This means the corrugations and the troughs defined by the corrugationsextend longitudinally or in the machine direction. This allows thepockets to continue expanding until the stretch limit of the nonwoven isreached, thereby maximizing the void volume within the core. In thisregard, the cell pattern is MD-biased (machine direction biased). FIGS.2C-2D illustrate workable or suitable cell patterns 240, 240′, usingdiamond shaped pockets P or rectangular shaped pockets P′. FIG. 2Eillustrates another diamond shaped bonding pattern 240″ usingintermittent bond points T1, T2. An additional benefit of CD elongatablepockets is that when the diaper is fitted to the user, stretching of thediaper around the body will cause some of the pockets to bepre-activated and elongated.

It should be noted that pockets or cells having expandable properties asdescribed above and in further embodiments may be strategicallypositioned in and around different regions of the core composite. Insome applications, such pockets may be provided in the central regionsso as to receive directly and accommodate intake. In other applications,the core composite may be configured to readily and rapidly receiveintake at the central regions and direct flow to the side regions. Insuch designs or configuration (but not all), it may be advantageous tolocate higher volume pockets in the side regions.

FIG. 4 illustrates various methods or techniques for riffling orcorrugating a sheet of the substrate A or C (forming or treating thesurface so as to exhibit corrugations or riffles thereon). FIG. 4 alsoillustrates equipment that may be suitable for use in riffling thesheet. Referring to the illustration provided above label (a) in FIG. 4,a nonwoven sheet 400 is moved, under tension, past a comb 480 with hard,protruding fingers 482 that sharply engage and temporarily deforms thetop surface of the sheet 400. This creates corrugations 430 or elongatedriffles (scratching) on processed sheet 402. The dimension of thecorrugations 430 will determined by the configuration of the fingers482, as well as the basis weight and/or stiffness of the non-wovenmaterial. A thinner or more flexible nonwoven will form finer riffles orcorrugations. Thicker non-woven can provide deeper corrugations and, asa result, greater elongation. Elongation may also be increased with thefrequency or pitch of the corrugations. Preferably, permanentdeformation (gouging, tearing, breaking, etc.) is avoided or at leastminimizes, so as not to compromise the structural integrity of thematerial. The nonwoven sheet may be riffled before application and priorto integration in a system for making the absorbent core, or, in asystem just upstream of SAP deposition. A roll of the riffled nonwovenmay initially be stored on and delivered via a spool. It is conceivable,however, that in further embodiments, a nonwoven substrate is riffled inplace, while it is serving as barrier to a population of SAP units.

According to another process option, illustrated and labeled as (b) inFIG. 4, the substrate 400 is placed into a engagement with a groovedroll 484 (or meshed slotted roll). The hard surface profile of the roll484 impresses the substrate with temporary grooves into the substrate400. The substrate 400 may be moved horizontally toward the grooved roll484, as shown in FIG. 4, and into engagement with the hard profiledsurface of the roll 484. Tension applied generally downward from andperhaps, generally perpendicularly to the horizontal direction causesthe sheet 400 to turn about the grooved surface, whereby the outsidesurface of the roll 484 penetrates the substrate's surface. The amountof tension applied on the substrate, the angle at which the tension isapplied on the moving substrate (downstream of the roller), the pitchand depth of the grooved roll's surface, and the dimensions and physicalproperties of the substrate, among other things, may be adjusted toachieved the desired riffled or corrugated substrate (with minimal or nopermanent deformation or tearing) for use in an absorbent corecomposite, according to the present disclosure. In accordance with yetanother process option, illustrated and labeled as (c) in FIG. 4, a pairof male and female grooved rolls 486 replaces the single roll to etchthe passing substrate. As shown, the substrate 400 is passed through theinterface of the two rolls 486 to produce the riffled or corrugatedsheet 402.

In the preferred embodiments, only one outside surface of the substrateis corrugated and employed in the absorbent core. It is conceivable,however, that the etching process can readily etch or scratch bothsurfaces of the substrate. Strategic use and placement of substrateshaving corrugations on both sides (e.g., in and about target areas ofinsult) may change the fluid handling performance in those areas.Corrugations on both sides may provide additional storage capacityand\or enhance ADL-type fluid handling performance. It may provide ahigher density of corrugations, if desired. Noting that a topsheet andADL layer is typically added above the substrate, placement of thecorrugations on the outside surface may not necessarily sacrificecomfort.

The simplified illustrations of FIGS. 5A and 5B depict another absorbentcore composite 520 having a means for accommodating SAP swell duringuse. As with the absorbent core composite 320 of FIGS. 3A-3D, theabsorbent composite 520 utilizes an elongatable substrate as a topnonwoven layer A over the SAP aggregate 535. The top nonwoven layer Amay be activated by SAP swell to increase the volume of the pocket orcell P and accommodate the additional SAP volume. In the specificconfiguration illustrated, the absorbent composite 520 has the topelongatable nonwoven layer A, a base nonwoven layer B, and SAPaggregates 535 situated therebetween. Referring to FIG. 5A, bond sites542 securing the top layer A to the base layer B mark the boundariesbetween SAP aggregates 535 and partly define individual pockets or cellsP that contain SAP aggregates 535 thereunder. The SAP aggregates 535 andthe pockets P are therefore spaced apart from adjacent SAP aggregatesand pockets.

In this embodiment, the top layer A is provided with two pleats 530 orsets of double folds. The pleats 530 may be formed on the source sheetof nonwoven as the sheet is being conveyed in-line toward a web of thebase nonwoven-SAP after SAP deposition. A pleat may be formed byapplying a pair of opposite-facing folds on the moving sheet, asgenerally known in the art. In the illustrated embodiment, a pair ofpleats 530 is provided for each pocket P and located to achieve thedesired pocket profile when the SAP 535 swells to fill the pocket P. Thefolds or pleats 530 are sized to facilitate transition of the pocket Pfrom a pre-active or thinner state to activated and full step (and otherstates of swell in between). It is desirable to maintain a smooth topsurface and profile so as not to compromise user comfort and riskpinching of the skin by the folds or edges. In this respect, the numberand size of folds and pleats may be coordinated with target swellcapacity and transition performance to achieve optimal results. Afterapplying the elongatable substrate over the SAP aggregates, theresultant composite may be passed into engagement with one or moreembossing rolls to apply the desired bonding or pocket pattern.

FIG. 5B shows the absorbent composite 520 in an a state of full SAPswell and in an activated state. For each pocket P, folds or pleats areno longer evident (completely unfolded), revealing instead, a somewhatrounded top surface rather than surface discontinuities marked by sharpedges or peaks. In further embodiments, pockets with elongatablesubstrates (such as those illustrated in FIG. 5A or FIGS. 3A-3D) may beemployed in conjunction with other means for pocket expansion orboundary breakage. For example, the pocket configuration of FIG. 3 or 5may be employed with the breakable bond pattern of FIG. 2E. The foldpattern and the bond point sizing may be coordinated, for example, sothat during use and upon liquid migration into the pocket, pressure dueto SAP swell acts to elongate the top substrate first. When the volumeof the pocket cannot be accommodated by pocket volume increase, certainof the bond points may be designed to break. In other designs, theabsorbent core design may call for some amount of bond breakage to occursimultaneous with or preceding the elongation of the elongatablesubstrate.

Programmed Bond Breakage

In further embodiments, the core construction is provided with pocketshaving dynamic boundaries or capacities and thus, mechanisms forincreasing void space. Specifically, mechanisms are established totrigger and allow for the pocket boundaries or break so as to relax therestraint on contained SAP material. Specifically, the bonds between thepockets are made to break or unzip so that the SAP can continue to swellbeyond the maximum volume of the pocket. In one embodiment,discontinuities in the bond lines are provided, whereby strength of theremaining bonding strips or points are designed to be less than SAPswelling pressure.

In an alternative embodiment, the layers may be secured by ultrasonicbond sites, which may be “tuned” to a certain minimum threshold strengththat may be overcome by SAP swell may overcome. Furthermore, the use ofadhesive bonds, perhaps in conjunction with ultrasonic bonding, may beemployed and “tuned” to provide a desired bond strength by changing andmanipulating the bonding pattern. For example, lower bond strength maybe achieved by smaller bond sites and higher bond strength may beachieved by larger or longer bond sites. In other embodiments, theultrasonic bonding may serve as the stronger or permanent (or latent)bonds, whereas adhesive bond sites serve as breakable bonds or barriers.Different manners of SAP swell and pocket volume expansion may beachieved through such manipulation and bond programming.

In one application, a heated calendar roll (or ultrasonic bonding) isemployed to heat, melt, and fuse the nonwoven layers at bond points.Generally, bond points below 1 mm wide break during normal use andincident of 75% (of swell capacity) SAP swell in pockets. Bond pointslarger than 1 mm diameter larger were observed to not break or breaklater. FIG. 2E illustrates a pocket pattern 240″ and configuration foran absorbent composite according to an embodiment employing breakablebonds, according to the disclosure. The absorbent composite utilizes adiamond embossing pattern 240″ with intermittent (spaced apart) bondpoints T1,T2 forming diamond shaped pocket. In this pattern, the bondpoints T2 located at intersections of bonding directional lines aresized to be permanent bonds while most, if not all, of the bond pointsT1 between the intersections are breakable. The bond points T2 at theintersections have a diameter of about 1.5 mm while intermediate bondpoints T1 have a diameter of about 1.0 mm (providing a bond area abouthalf the size of the bond area at the intersections). Many of thesesmaller bond points T1 are expected to breach at high SAP swell states(of the adjacent pockets).

In another embodiment, water sensitive adhesive may be used in thelamination. The adhesive weakens when contacted with water and wetted,and is overcome by increasing swell pressure. Adhesives used to form awater soluble bond may employ as components, polymers that make watersoluble resins, including ethylene vinyl alcohol and/or polyvinylalcohol.

In yet another embodiment, hotmelt bonding may be employed (e.g.,thermoplastic particle) to serve as the programmable, breakable bondsite. In this mechanism, the hotmelt/SAP combination serves as theadhesive during manufacture and passive use of the absorbent article.When wetted, the SAP swells and weakens before breaking. As with theother proposed bonding site mechanisms, the hotmelt/SAP bond sites maybe used in conjunction with one or more of the other bonding mechanismto achieve the desired breaking and pocket volume expansion effect.

Substrate Control

In some embodiments, volume expansion is effected by employing a dynamiccomposite layer or component. In one technique, one layer is provided bya relatively weak material that is overcome by the aggregate of SAPparticles swelling beyond the pocket volume. For example, anintermediate layer, such as substrate B in FIG. 3C, may be made oftissue material that opens or is otherwise compromise by the swellingSAP aggregate, thereby expanding the void capacity. Suitable candidatesfor the material include dry-crepe tissue, which elongates when wetted.A low wet strength tissue (e.g., low basis weight tissue) may also beselected, which weakens when wetted and is readily overcome (breaks) bySAP swell. A third material option is a slitted substrate. A fourthoption is a material that has been weakened or perforated so as to beable to open up by the force exerted by the swelling SAP. In theseembodiments the swollen SAP may no longer be fully contained by thematerial components of the core. Provision for the storage andcontainment of this swollen SAP would need to be made within otherelements of the absorbent article. In any case, upon contact with liquidor with increasing pressure asserted by a collectively swellingaggregate of SAP, the layer opens to communicate the SAP aggregatebeyond the initial fixed volume of the pocket

A “tissue” is generally a (paper) cellulose-based nonwoven as opposed toa synthetic nonwoven. Preferably, the tissue is provided as a bottom orbase layer of the absorbent composite, if it is intended to function asa breakable substrate. As such, it may be readily supported by abacksheet beneath it for contain liquid. In preferred designs, it wouldbe advantageous to size and\or secure the backsheet and tissue layers soas leave expansion (containment) space beneath the tissue layer. Forexample, the backsheet may not be completely or tightly bonded to thecore. Alternatively, a bulky nonwoven layer may be employed to providethe thicker profile.

Further Core Composite Design Considerations

In several applications wherein SAP is at least partly contained orimmobilized by a fibrous network or other matrix, a procedure may beemployed to facilitate the deposition of the SAP particles within thematrix. In the embodiment wherein a bulky nonwoven is used as asubstrate to stabilize the SAP particles, the web carrying the SAP onthe substrate may be vibrated or shaken to impart energy on thesupported SAP particles. The added energy enhances the matrix′ abilityto capture and embed individual particles therein. In anotherembodiment, energy is imparted on the SAP particles by applying a vacuumto the outside of the substrate, which draws the particles toward andinto the substrate. In either case, suitable equipment may be positionedimmediately downstream of where SAP particles is deposited on the web ofsubstrate.

In another embodiment, SAP of different absorption properties, i.e.,absorbency under load (AUL), absorption rate or aggregate flowproperties, i.e., liquid permeability, may be deposited in specificMD-stripes. For example, a stripe of approximately the same width as thelength of a diaper target zone is deposited as a central zone with twostripes comprising another SAP type adjacent and abutting both sides ofthe first stripe. The SAP arrangement will be utilized in a CD-diaperforming process. That is, the product is formed with the longitudinaldirection of the product oriented in the transverse or CD direction inthe diaper converting line.

FIGS. 8A-C depict three core composition design patterns (810 a, 810 b,810 c) in which different grades or types of SAP material are positionedstrategically to achieve desired absorption characteristics. In atechnique that may be described as cross-directional (CD) profiling,certain centralized target areas or zones 822 of the core are providedwith slow absorbing SAP with high absorption underload (AUL) and highpermeability. In contrast, the outside areas or zones 824 are providedwith slow absorbing SAP with low AUL and low permeability. The effect isthat the initial intake in the central region 824 is only partiallyabsorbed by the slow absorbing SAP with excess fluid flow beingdistributed to the outside regions, where it is absorbed rapidly andthus, stored. Higher performance is achieved primarily because theinitial liquid insults are encouraged to spread and flow to the ends ofthe diaper due to the slower absorption rate or higher permeability ofthe first SAP which allows the liquid to flow through the target zoneand into the end zones. For subsequent intakes, the central regionprovides yet remaining capacity to receive some or all of the additionalfluid.

SAP Permeability

For present purposes, a SAP gel bed permeability greater than about 40Darcys is considered a high permeability SAP. A permeability less thanabout 5 Darcys is considered a low permeability SAP. In this respect,gel bed permeability is measured under a 0.3 psi load using 0.9 percentsaline solution on a 40-50 mesh particle size cut by the methoddescribed in Buchholz, F. L. and Graham, A. T., “Modern SuperabsorbentPolymer Technology,” John Wiley & Sons (1998). page 161. As known to oneskilled in the art, the term “Darcy” is a CGS unit of permeability. OneDarcy is the permeability of a solid through which one cubic centimeterof fluid, having a viscosity of one centipoise, will flow in one secondthrough a section one centimeter thick and one square centimeter incross-section, if the pressure difference between the two sides of thesolid is one atmosphere. It turns out that permeability has the sameunits as area; since there is no SI unit of permeability, square metersare used. One Darcy is equal to about 0.98692×10⁻12 m² or about0.98692×10⁻⁸ cm².

Absorbency Rates

Generally, most commercial SAPs have a vortex time ranging from 40-90seconds. A vortex time of less than 40 would be considered a fast orhigh absorption rate SAP for present purposes. A vortex time of greaterthan 100 would be considered slow, again for present purposes. Asunderstood by those skilled in the art, the Vortex Time Test measuresthe amount of time in seconds required for a predetermined mass of anabsorbent polymer to close a vortex created by stirring 50 millilitersof 0.9 percent by weight sodium chloride solution at 600 revolutions perminute on a magnetic stir plate. The time it takes for the vortex toclose is an indication of the free swell absorbing rate of the absorbentpolymer.

AUL (Absorbency Under Load):

For present purposes, an absorbency of greater than about 15 g/g at aload of 0.09 psi would be considered high AUL. As understood by thoseskilled in the art, the test measures a superabsorbent's ability toabsorb 0.9% saline solution against a defined pressure. Test proceduresentail placing a superabsorbent a plastic cylinder that has a screenfabric as a bottom. A weight or load giving the desired pressure is puton top. The cylinder arrangement is then placed on a liquid source. Thesuperabsorbent is soaked for one hour, and the absorption capacity isdetermined in g/g. See European standard EDANA ERT 442—GravimetricDetermination of Absorption under Pressure or Absorbency Under Load. Seealso the AUL-test found in column 12 in U.S. Pat. No. 5,601,542.

FIG. 14 illustrates, in simplified fashion, a system 1400 and process bywhich a sheet of an absorbent composite may be made according to thedisclosure. In one respect, the system previously described of FIG. 1Dmay be modified to incorporate elements of the system of FIG. 14 to makean absorbent composite exhibiting SAP variations in cross machinedirection. As described before, a web or sheet of a first fabric orsubstrate 1425 is preferably conveyed to present a planar surface. Thesubstrate 1425 is passed beneath a SAP dispenser 1480 with means forsegregating different types of SAP 1435 and depositing SAP types throughapertures strategically positioned relative to the moving substrate1425. In the illustrated embodiment, the dispensing apertures arepositioned to deposit SAP at spaced apart points, which create laterallyspaced apart lanes 1437 of SAP on the moving substrate 1425.Furthermore, SAP-free lanes 1439 are provided between the SAP lanes1437.

Subsequent to SAP deposition, the second fabric 1455 is applied over theSAP-lanes creating the desired laminate. As required, the resultantlaminate may be passed to a bonding area 1442 to apply the desiredbonding pattern 1440 on the laminate. In an absorbent composite takenfrom the laminate, the SAP-free lanes between strips of SAP can act aschannels for quickly directing liquid received therein.

SAP-free lanes may also be formed by providing folds in the substrate1425 before the sheet is passed to the SAP dispenser 1480. Referring toFIG. 14, the folds may be located where the SAP-free lanes shown. Inthis embodiment, the SAP dispenser is selected and\or operated to applySAP generally uniformly across the substrate 1425, including over thefolds. Hotmelt adhesive is the applied over the SAP to secure it to thesubstrate. Thereafter, the folds may be opened (e.g., by a tenterdevice) to reveal the SAP-free lanes. In a further embodiment of theabsorbent composite, the folds are maintained in the finished absorbentcore composite rather than opened. In this way, the substrate 1425functions as an elongatable substrate that may be activated by SAP swellduring use.

Additionally, another feature that can be added in the constructiondescribed above is the addition of a small percentage of ion-exchangeparticles 907 to a second SAP mixture deposited in target areas, andmore specifically, the end zones (outside zones 924) away from thepoints of insult. It has been found that the ionic strength of the urineas it passes through a bed of SAP materials (S) increases because of theSAP absorbing its water content. This is shown in the diagram of FIG.9A, which illustrates the receipt area 922 of an absorbent core 910 forinsult and the typical travel (see directional arrows) of liquid in thecore 910 after initial receipt in central zone 922. The perimeter ofcore 910 is defined by a pair of end edges EE and a pair of side edgesSE. The primary insult target 922 of the core 910 (where liquids aretypically received by the core 910) is generally in and about the centerof this defined perimeter. Directional arrows in FIG. 9A indicate thegeneral advance or spread of the liquid after receipt.

The graph 901 of FIG. 9B is drawn to correspond with the expanse of thecore 910 in FIG. 9A. The graph 901 illustrates the change in theliquid's ionic strength as it travels along the core 910 and the effectof this change on SAP absorbent capacity. Generally, the absorbentcapacity of SAP is reduced as the ionic strength of the liquid beingabsorbed increases. See graph 903 of FIG. 9D. Because SAP swellingdecreases with the increase in ionic strength of liquid being absorbed,SAP (S) that is furthest away from the liquid source and which contactsliquid having higher ionic strength, will have lower swellingproperties.

The graph 902 of FIG. 9C illustrates the effect that the introduction ofion-exchange particles has on the SAP absorbent capacity of the sameareas of the core 910. The introduction of ion exchange particles alongthe path of the liquid, including in these SAP areas (S) (specifically,the end zones 924) will lower the ionic strength of the liquid beingabsorbed there, thereby maintaining the absorption capacity of the SAP.Ion-exchange particles 907 in the fluid path restores capacity of theSAP by lowering the ionic strength of the urine reaching the ends of thecore 910. So for example, a cation ion exchange resin can remove orlower the concentration of multivalent cations like Ca++ and Mg++present in urine, hence effectively lowering the ionic strength of theurine. A typical cation exchange resin is Dow Amberlite 200C Na, used atbetween 1-10% of SAP content.

Accordingly, higher performance will be achieved with this constructionsince more liquid can be absorbed by the SAP (S) at the end zones (924).

In still another embodiment, narrow lanes that are relatively SAP-freeare formed for the purpose of creating stripes used in producing diaperwidth strips that are bonded and sealed at the slit lines. Becauseseveral diaper widths strips can be cut from the material envisioned bythis process, producing these narrower strips with sealed edges haveseveral advantages. These include minimizing potential SAP loss duringsubsequent handling. This also obviates the need for a separate corewrap when assembled into a diaper.

The SAP-free lanes can also readily serve to accommodate bond lines infurther processing. Additionally, these lanes can provide fold linesrequired of the composite design.

In another embodiment, a liquid phase/spray application of hotmeltadhesive is utilized to provide yet another form of binder or matrix tostabilize and partially immobilize SAP particles. In an extrusionprocess, hotmelt adhesive is forced through small holes which, incombination with air attenuation, produces elongated polymer strands orfiber. Deposited on the substrate, the elongated polymer strandsestablish a fibrous network capable of holding the SAP particles.

The simplified illustration of FIG. 15 provides a system 1500 that maybe employed to apply the fibrous network. As before, a SAP dispenser1580 may be used to deposit SAP 1535 on a moving fabric or substrate1525. In the illustrated embodiment, SAP 1535 is applied uniformlyacross the planar surface of the substrate 1525 as it passes beneath thedispenser 1580. The SAP 1535 may be held in place, thereafter, by avariety of mechanisms, including applying suction applied to theunderside of the substrate 1525, as discussed previously. Then, thesubstrate 1525 and SAP 1535 combination is passed beneath a hotmeltfiber extruder 1586 that dispenses and applies hotmelt fibers 1539 overthe SAP 1535 and substrate 1525. The resultant composition 1510 is shownin the inset of FIG. 15.

Nonwoven Design and Selection

To achieve core performance objectives, the various core compositecomponents may be altered or specifically designed (individually or incombination). The core performance properties of interest includeabsorption properties, including rate and capacity, permeability, rewetperformance, and structural integrity.

The core composite typically includes a permeable top layer thatreceives intake and then helps contain absorbent material within thecore. In one design, a nonwoven material may be selected that has anoutside surface that is more open than the inside surface. The more opensurface serves to readily receive SAP particles thereon, and in thatrespect, binds and at least partially immobilizes the SAP particles. Incontrast, the opposite surface is relatively dense and advantageouslymore impermeable. This surface acts to block the penetration of SAPparticles beyond the network of fibers presented at the more opensurface. While SAP particles, particularly the smaller ones, arereceived and slightly encapsulated by the substrate, they are preventedfrom passing through the substrate. As mentioned previously, thesubstrate may be energized to facilitate receipt of the SAP particles bythe more open surface.

The nonwoven described above is sometimes called a “bulky” nonwoven.Reference may be made to co-pending '051 patent internationalapplication for further description of suitable bulky non-woven materialand selection. The “bulky” nonwoven referred to herein is, and provides,an open, fibrous network or web of hydrophilic but non-absorbent fibres.Further, as used herein, a bulky nonwovens is a fibrous web materialhaving a thickness of between 100 μm and 10,000 μm (preferably 1,000 μmto 5,000 μm), basis weight between 15 g/m² and 200 g/m² (preferably,between 20 g/m² and 80 g/m²), and density between 0.01 g/cc and 0.3 g/cc(preferably between 0.01-0.08 g/cc). Moreover, the bulky nonwoven willhave an effective pore diameter between 300 μm to 2000 μm.

In further applications, it may be advantageous to employ consolidatedbut unbonded or lightly bonded nonwoven as one of the substrates. Theunbonded surface may serve well embedding and supporting the SAPparticles. The outside may be bonded, however, so as to maintainstructural integrity and impermeability. In further applications, theunbonded surface may be bonded after application of SAP particlesthereon by using hotmelt or infrared heating. This procedure may benecessary or advantageous, as it imparts structural integrity to thecomposite's nonwoven layer. Although an already bonded nonwoven layermay have been used, the bonding in place technique allows for the SAPparticles to be bonded and supported also, in one bonding operation. Byusing hotmelt or IR to bond the nonwoven (with SAP) after application ofSAP, the nature of SAP encapsulation and hence the composite integrity,swelling properties and fluid flow or permeability characteristics canbe varied and controlled.

In specific embodiments, suitable bulky/high loft materials contemplatedfor use in the above suggested applications are a type of “through airbonded” nonwovens. The nonwovens are made by taking a carded web or matof fibers and using hot air to bond the fibers at the points where thefibers intersect or join. The hot air “blowing” through the web servesto keep the fibers separated to some extent and uncompacted. Theresultant structure is, therefore, fairly open but fixed by bonds formedbetween the intersecting fibers. (This is different from the traditionalprocess by which non-bulky, regular nonwovens are made, wherein anunbonded mat of fibers is passed through heated bonding rolls thatcompact the fibers and form a thin web of nonwoven, and leave anembossed bonding pattern). In an exemplary method of manufacturing theabsorbent composite, a web of carded, unbonded fibers (e.g., PET fibers)is conveyed and SAP is deposited on the web. Hot air or other suitablemeans is then used to bond the SAP and the non-woven in place.

Hotmelt Application Design and Selection

As described previously, in one embodiment, a liquid phase/sprayapplication of hotmelt adhesive is utilized to provide yet another formof binder or matrix to stabilize and partially immobilize SAP particles.In an extrusion process, hotmelt adhesive is forced through small holeswhich, in combination with air attenuation, produces elongated polymerstrands or fibers. Deposited on the substrate, the elongated polymerstrands establish a fibrous network with capacity to hold the SAPparticles.

In an alternate method, powdered hotmelt adhesive particles can be mixedwith superabsorbent particles and the mixture of unbonded hotmeltparticles and superabsorbent particles is applied to the nonwovensubstrate. Application of heat to the composite will cause the hotmeltadhesive powder to melt and bind the SAP and nonwoven substrate. Theapplication of heat can be accomplished through IR (infra-red) radiationmethods, heated calendar rolls or other means.

The selection of hotmelt material and processes as a design element canachieve particularly improved product performance. In furtherapplications, the ratio of hotmelt particles to superabsorbent particlesis selected to achieve an optimum balance of dry integrity and restrainton SAP swelling. The ratio of the number of SAP particles to hotmeltparticles will determine for example, how many bonding points,contributed by the hotmelt particles, per SAP particle are possible. Theratio is determined from the weight percentage, particle sizedistribution and polymer density of each component. For example:

hotmelt particle size range: 0-120 u 0-200 u 0-300 u particle ratio (HMto SAP): 46.79 27.06 9.75 optimum adhesive content: 2.1% 3.7% 10.3%

Here, optimum adhesive content is defined as one particle of hotmelt perparticle of SAP and uniform mixing is assumed. The ratios shown are forcommercially available SAP and hotmelt particles. The chart of FIG. 9provides particle size distribution for a SAP material SAP (W-112 fromNippon Shokubai). The hotmelt particles are commercially availablematerials from Abifor and have the following particle size distributionprovided in FIG. 10. The hotmelt to SAP weight ratio can range from1%-30% of SAP content, preferably from 4% 12%.

The selection of hotmelt material and processes as a design element canachieve particularly improved product performance. In some applications,water sensitive hotmelt particles may be employed as a mechanism forincreasing void space (swell volume). Specifically, a hotmelt isselected that is sensitive to wetting (e.g., an SAP based hotmelt) andthus, to receipt of liquid intake in the absorbent core pockets. Thesehotmelt particles break down as the SAP particles around it swell withliquid absorption. This relieves the SAP particles from the hotmelt'sbind and allow the SAP to swell unrestricted. An example of a watersoluble hotmelt is the modified polyvinyl alcohol resin (Gohsenx Lseries, Nippon Gohsei). An example of a water sensitive hotmelt isHydrolock (HB Fuller).

SAP Selection and SAP Aggregate Constitution

As described previously, the pockets of SAP aggregate need not beuniformly provided or distributed across the core composite. Variationsin pocket size and shape, pocket volume, SAP volume, SAP-pocket volumeratio, and SAP concentration may be manipulated to achieve performanceobjectives. In addition to those design parameters, the distributions orconstituents of the pockets, including the SAP aggregate, may be variedas design elements.

In various embodiments, absorbent composite design takes into accountthe size and distribution of the SAP particles. As general guidingprinciples, the permeability of a SAP assembly increases linearly withparticles sizes (large SAP particle sizes have highest permeability).For example, doubling the particle size will double the permeability ofthe SAP assembly. Further, the permeability of a SAP assembly decreaseswith loading or swelling restraint (effect seen with small pockets).Finally, permeability decreases with increasing saturation (afterinitial 25% saturation).

In one embodiment, the SAP aggregate constitution may be selected toinclude a certain mix of smaller particles that penetrate the surface ofthe nonwoven layer and larger particles that generally remain above thenonwoven surface. The nonwoven surface may also be prepared orpreselected based at least partially on the desired particle filtrationeffects. The result is a layering of the SAP particles at the interfaceof the non-woven and the SAP (see e.g., absorbent composite 1110 of FIG.11). Such layering and separation of SAP particles can be utilized tochange the fluid uptake behavior of the segregated layers formed. Thelayer formed from the larger particles will have a higher permeabilityrelative to the layer formed from the smaller particles. Such anarrangement can encourage the lateral flow of liquid during the insultresulting in more fluid distribution and spreading. To aid thefiltration technique, the nonwoven may be energized during themanufacturing process to impart and encourage particle separation in theSAP.

In methods of manufacturing the preferred composite, the multi-layercore substrate may be pre-fabricated by a supplier according tospecification. Suitable “through-air bonded non-wovens” may be made in asingle process by combing PP/PE/PET fibers into a web and then bondingthe web by blowing hot air through the non-woven. As a result, thermalbonds form between the crossing fibers. As generally known in the art,multi-layer structures may be made by combing different layers ofnonwoven on top of each. For example, three combs may be provided tobuild up three different layers of nonwoven, each layer having adifferent combination of fibers, density, and thickness. Preferably, aroll of the prefabricated multi-layer substrate is conveyed onto amanufacturing line whereupon a SAP mixture is deposited on the movingcore substrate.

In the alternative, the multi-layer core substrate may be made on-siteand further, on-line. For example, three separate rolls or sheets ofhigh loft nonwovens maybe delivered (e.g., unwound) and combined into amulti layer web. The layers may be bonded by applying a layer of hotmeltadhesive between each layer of nonwoven (e.g., applied by spray or slothotmelt coater). Alternatively, the nonwoven layers may be point or linebonded by applying heated engraved/patterned calendar roll onto the web.An ultrasonic bonding method may also be employed. In any case, thermalor ultrasonic bonding may be performed before or after depositing SAPonto the multi-layer core substrate.

To reduce cost and process complexity, each of the SAP intended for eachlayer is joined with and delivered onto the multi-layer substratesimultaneous with the other SAP constituents. SAP grades are selectedhaving the desired particle sizes and ranges. The arrangement ofdifferent density nonwovens will act to separate and place the SAPparticles in the appropriate layers. It is contemplated, however, thatcertain applications may require separate and independent deposition ofthe different SAP populations directly onto the intended core substratelayer. In one example, the smallest SAP particles are applied directlyonto highest density layer, the medium size particles applied to theintermediate layer, and largest particles applied to the lowest (andtop/bodyside) density layer. In a more specific example, the bottomnonwoven layer is first conveyed and then deposited with the supply ofsmall SAP particles. Then, the intermediate layer is applied over thefirst nonwoven layer followed by deposition of medium size SAP particlesdirectly onto the exposed surface of the intermediate layer. The topnonwoven layer is then applied over the SAP-saturated intermediatelayer, followed by larger particle size SAP being deposited directlyonto the top nonwoven layer.

In certain embodiments, a disposable absorbent article incorporating theabsorbent core composite will include a topsheet and backsheet. The corecomposite is sandwiched between the topsheet and backsheet, with thetopsheet providing the bodyside liner or cover. In further embodiments,the bodyside material layer of the core composite functions as thetopsheet, thereby eliminating the need for the topsheet.

For purposes of this description, low, medium, and high densitynonwovens are nonwoven materials having a density of 0.01 to 0.03 g/cc,0.03 to 0.08 g/cc, and 0.09 to 0.12 g/cc, respectively. The preferredthickness of the low, medium, and high density nonwoven layers is 1.5 mmto 5 mm, 0.6 to 3 mm, and 0.15 to 0.6 mm, respectively. Thespecification depends on the basis weight and density of the nonwoven,as shown in Table 1 below. Table 1 below may be referred to in selectingsuitable low, medium, and high density nonwovens to satisfy absorbentcomposite design requirements. Moreover, preferred nonwovens will becommercially available multi-layer webs of different fiber denier anddensity for each layer, typically using carding technology with multipleformers. An example of such a suitable web would be a double or triplelayer structure typically used as an ADL (acquisition-distributionlayer) available from Libeltex Nonwovens, Belgium, (Dry Web TDL2, SlimCore TL1, TL4, TL5).

TABLE 1 Web Thickness (in microns) vs. Basis Weight and Density WebThickness (in microns) vs. Basis Weight and Density Web Density 0.010.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 0.12 0.2 0.3 Basis 15 1500750 500 375 300 250 214 188 167 150 125 75 50 Weight 20 2000 1000 667500 400 333 286 250 222 200 167 100 67 30 3000 1500 1000 750 600 500 429375 333 300 250 150 100 40 4000 2000 1333 1000 800 667 571 500 444 400333 200 133 50 5000 2500 1667 1250 1000 833 714 625 556 500 417 250 16760 6000 3000 2000 1500 1200 1000 857 750 667 600 500 300 200 70 70003500 2333 1750 1400 1167 1000 875 778 700 583 350 233 80 8000 4000 26672000 1600 1333 1143 1000 889 800 667 400 267 90 9000 4500 3000 2250 18001500 1286 1125 1000 900 750 450 300 100 10000 5000 3333 2500 2000 16671429 1250 1111 1000 833 500 333 110 11000 5500 3667 2750 2200 1833 15711375 1222 1100 917 550 367 120 12000 6000 4000 3000 2400 2000 1714 15001333 1200 1000 600 400 130 13000 6500 4333 3250 2600 2167 1857 1625 14441300 1083 650 433 140 14000 7000 4667 3500 2800 2333 2000 1750 1556 14001167 700 467 150 15000 7500 5000 3750 3000 2500 2143 1875 1667 1500 1250750 500 160 16000 8000 5333 4000 3200 2667 2286 2000 1778 1600 1333 800533 170 17000 8500 5667 4250 3400 2833 2429 2125 1889 1700 1417 850 567180 18000 9000 6000 4500 3600 3000 2571 2250 2000 1800 1500 900 600 19019000 9500 6333 4750 3800 3167 2714 2375 2111 1900 1583 950 633 20020000 10000 6667 5000 4000 3333 2857 2500 2222 2000 1667 1000 667

A typical core composite will be provided with SAP in the range of about100 gsm to 500 gsm. Of this amount, about 5% to 75% may be in one singlelayer of the absorbent composite. The highest density layer may have aslittle as about 0.5% to 5% of the total SAP amount. It should be notedthat some SAP may not penetrate onto the nonwoven layers at all, but siton the outside surface. In exemplary two layer constructions, theaverage size dimension of SAP particles (i.e., width or diameter)targeted for a first or high density layer (and which, will generallypass through a nonwoven layer above it) is 0-300 microns. The second orlower density layer will contain larger sized particles, includingso-called medium size and large size SAP particles typically in the300-850 microns range. In a three layer composite, the large SAPparticles, which are expected to not penetrate the intermediate layer,will be retained in the top or lower density nonwoven layer and have anaverage size dimension greater than 600 microns (in the 600-850 micronsrange), and the medium size SAP particles will be in the range of 300 to600 microns (in the intermediate density nonwoven layer). Accordingly,the smaller size particles will be in the range of 0 to 300 microns (inthe high density nonwoven layer).

FIG. 11 provides, in elevated cross-sectional view, an absorbentcomposite 1110 having a multi-layer configuration discussed above. Ahigh density nonwoven serves as the base layer NW1 and is showncontaining a representative population small SAP particles. Anintermediate layer NW2 is provided by a medium density nonwoven andcontains a representative population of medium size SAP particles S2.Finally, atop the intermediate layer NW2, a low density, open nonwovenprovides a top layer NW3, which, as incorporated into a disposableabsorbent particle is situated bodyside (closest of the composite'slayers to the user's skin) and likely adjacent a topsheet.

In some embodiments, the SAP particles penetrate well into themulti-layer composite and may be bonded therein (e.g., by application ofhotmelt particles, spray hotmelt, etc.). No additional cover layers arerequired. In making the disposable absorbent article, a topsheet isapplied directly over the multi-layer composite. In other embodiments,an additional nonwoven layer or even tissue is applied as a cover layerover the composite to further secure the SAP. Alternatively, theadditional nonwoven or tissue may be wrapped all the way around(enveloping) the multilayer composite construction. In anotheralternative embodiment, hotmelt fibers is sprayed over the top surfaceof the multilayer construction maintain the SAP in place.

It should be noted that particle size determination as alluded to above,and in the selection of such particles in a corresponding design ormethod, is largely implemented by equipment operated to dispense theSAP. In suitable applications, a sieve will be provided with theappropriate screen or mesh. The screen or mesh will be specific to thesize of SAP particles being separated. Furthermore, the separationand\or mixing of SAP particles may be partly or entirely performed inprocess, preceding to or in conjunction with SAP deposition, or prior tothe manufacturing process.

An absorbent core composite sheet providing an absorbent constructionaccording to the above description and FIG. 11 may, subsequent to SAPdeposition and securement, be bonded to further secure the SAP. Asdescribed above, a bonding pattern applied to the sheet creates pocketsof SAP aggregates. For example, a diamond embossing pattern as describedpreviously in respect to FIG. 2 may be employed to bond the outsidenonwoven layers. In alternative embodiments, the composite sheet may beslit and cut longitudinally to produce multiple core composites orsheets. In such an application, the source core sheet for slitting maybe delivered with uniform thickness and without pockets.

When utilizing hotmelt particles as binder for SAP preservingaggregates, the SAP particle size and quantity relative to hotmeltparticles may be a design consideration for improving or preserving SAPperformance. Generally, the amount of hotmelt particles must be adequatefor binding the SAP. Excess hotmelt particles or material may, however,work to reduce capacity and absorption rate of the SAP particle. This isdue to the hotmelt material possibly coating or blocking the SAPparticle, and as well, restricting movement and swelling. In preferredembodiments, the ratio of hotmelt particles to SAP particles isone-to-one.

In further embodiments, the SAP aggregate constitution may include acombination of SAP particles, in the spherical and/or flake forms, andSAP in the superabsorbent fiber form (sometimes referred to as SAF).Specific combinations and ratios may be selected to achieve desiredfluid or absorbent properties, as well as structural properties. Forexample, in embodiments wherein a bulky layer is employed with acombination of spherical SAP and superabsorbent fibers, smallerspherical SAP will gravitate to and penetrate the open fibrous surfaceof the bulky nonwoven. In contrast, the superabsorbent fibers will tendto settle atop the surface.

In another embodiment, the SAP aggregate constitution is populated orrather, infiltrated, by smaller inert particles which positionthemselves between the larger SAP particles. This increased spacingincreases the permeability of the SAP aggregate. The void volumeavailable within the aggregate is increased due to the spacing. As aresult, the SAP particles located inside the aggregate are less likelyto experience gel blocking. Preferably, the spacing particles are inertso as not to alter the SAP properties, and sufficiently small so as notto significantly increase the volume of the aggregate, the pocket, orcore composite.

An example of a suitable inert particle is an ion exchange resinparticles (as also described previously). In this mode, it can bedistributed throughout the absorbent composite, including sectionsintended as target area. As described previously, the addition of ionexchange particles will serve to increase the capacity of the SAP at thetarget zone and throughout the core because it will reduce the ionicstrength of the incoming fluid (urine). Typical ion exchange resinparticle size used in these applications will be about 300-400 micronsin size. Another suitable, and readily available, source of a spacingparticle are microporous silica gel beads. Silica gel is an amorphousform of silicon dioxide that is synthetically produced in the form ofhard regular beads. It has a microporous structure and is typically usedas a high capacity desiccant. The gel beads are available in suitableparticle sizes between 150 microns-2000 microns or greater. In additionto functioning as a spacer, the silica gel can also be used as a carrierfor other ingredients such as fragrances and odor control agents. Theseingredients are pre-applied to the microporous beads and will becontained within the bead when deposited with the SAP.

To illustrate, FIG. 12 provides a general depiction of the distributionand mutual spacing of SAP particles S as found in an absorbent corecomposite, with and without the aid of inert particles (ii). On the leftportion of FIG. 12, a normal distribution of the SAP particles (S) areshown relatively firmly packed in a given volume or area. Then, a jointpopulation of inert particles (ii) and SAP (S) is introduced into thesame area or volume. As shown on the right side of FIG. 12, the inertparticles (ii) situate themselves between SAP particles (S). As aresult, the spacing between SAP particles is increased, even with inertparticles randomly occupying some of the space. There are less SAPparticles (S) in the same area. In FIG. 12, the average dimension (i.e.,diameter) of the inert particles is less than about 40% of that of theSAP particle (for illustration). It should be noted however, that FIG.12, shows only the area. The actual space between SAP particles is inthree dimension and thus, the increase in volume (not area) between SAPparticles (with the inert particles (ii) is greater (one degree of orderhigher than area calculation).

In a further embodiment, the SAP aggregate constitution may include awater-soluble particle to perform the spacing function. The spacingparticle in this constitution will, however, dissolve upon liquidintake. This serves to provide yet additional void volume, and toaccommodate SAP swell. An example of a suitable source of water-solubleparticle is a polyvinyl alcohol. A low molecular weight, cold watersoluble PVOH may be used (i.e., Selvol 203 (Sekisui SC), Poval PVA-203(Kuraray)).

In a yet another embodiment, wherein a hotmelt adhesive is employed,heat sensitive, volatile particles are employed as spacers or spacingparticles. When a bonding step applies heat to activate the hotmelt, thespacer particle evaporates leaving the SAP, the hotmelt particles, andadditional void space between SAP particles (see FIG. 13). Selection ofsuitable volatile particle must, of course, take into considerationpossible safety and practical concerns, including the level of energyrequired to activate the material. The material is incorporated materialin solid form to the SAP mixture for deposition and then vaporizes uponthe application of heat or vacuum. Possible sources are dry ice andiodine.

FIG. 13 provides a graphical chart 1300 that illustrates the variousmechanisms described above, and the interactions between SAP aggregateconstituents. Each of four rows or panels of the chart 1300 illustratethe packing (i.e. spacing and distribution) of SAP particles andnon-absorbent particles, including spacing particles, in arepresentative portion of the absorbent composite. The top row (a)relates to the addition of hotmelt particle to the SAP population.Before bonding, the hotmelt particles occupies a small space between SAPparticles. During bonding, the hotmelt particle melts, leaving spacebetween SAP particles. As illustrated by the right most frame, SAP laterswells to fill up much of the space between SAP particles. The next row(b) illustrates particle packing when inert particles is added—to themix of hotmelt particle and SAP. As shown in the first frame, the inertparticles help to space the mutually space SAP, even after the hotmelttransforms to a coating after bonding. Later, when a SAP particle beginto swell, it can expand into the void left by the hotmelt particle.

The next row (c) illustrates the addition of volatile particles to themix of hotmelt and SAP. The volatile particles help to mutually spacethe SAP particles and increase permeability. As shown in the rightmostframe, the inert particles continues to help space the SAP from eachother, even during product use and SAP swell. FIG. 13 depicts, in thelast row (d), the addition of water soluble particles into theSAP-hotmelt mix. The water soluble particles remain in the mixture evenwhen the hotmelt particle disappears after bonding. The water solubleparticles dissolve, however, in use, as the pocket begins to takes onwater content. As shown to the right of FIG. 13, SAP occupies volumebetween SAP particles and helps to space the particles, but gives upthis space to expanding SAP particles during use.

Each of the schematics of FIGS. 16 and 17 illustrates an exemplarysystem (1600, 1700) and method for making an absorbent core compositeaccording to one or more of the embodiments described above. In a methodaccording to FIG. 17, a sheet or fabric 1625 is dispensed from spool1620 and carried along a production line on a conveyer belt 1605. Thesheet or fabric provides the substrate 1620 of the finished absorbentcore composite. In various preferred embodiments, the substrate 1625 isnonwoven thermo plastic material. The sheet 1625 is subjected to ariffling or corrugating process by which one surface of the sheet isetched or scratched to produce riffles or corrugations thereon, aspreviously discussed in respect to FIG. 4. In this example, a pair ofgrooved rolls 1686 (one female and one male) is employed to create thedesired corrugation dimensions and pitch. The corrugations are directedin the machine direction. Adhesive is then applied on the corrugatedsurface in preparation for and as required of SAP to be deposited on thesurface (see adhesive applicator 1688) In this embodiment, two SAPdispensers 1680 a,1680 b are employed serially deposit SAP on theriffled or corrugated surface. The first dispenser 1680 a operates todeposit SAP almost all the way across the moving substrate. The secondSAP dispenser 1680 b operates to deposit SAP onto a central region ofthe substrate, thereby supplementing the SAP amounts previouslydeposited in that region. For some absorbent composite designs whereinSAP amounts vary in the longitudinal direction, the second SAP dispenser1680 b may be operated intermittently. See, for example, the coredesigns of FIG. 6 and the accompanying description. The second SAPdeposited may also be of a type different from the first SAP deposited,and\or contain a constitution different from the first deposit (e.g.,contain non-SAP materials not provided with the first SAP). The secondSAP may, for example, exhibit properties particularly advantageous foruse in the central region of the finished core. In this embodiment, theSAP is secured on the sheet 1625 and the sheet 1625 is secured to theconveyor belt 1605 by a vacuum system applying suction to the sheet1625.

Referring again to FIG. 16, a second sheet or fabric 1625 issimultaneously dispensed from a second supply spool and carried along aproduction line on a second conveyer belt 1607. In various embodiments,the second fabric 1655 is a nonwoven material that provides the topsubstrate or cover layer for the absorbent core composite. In thisembodiment, the top substrate is also elongatable. Accordingly, thesecond sheet 1655 is also subjected to a riffling or corrugatingprocess. Thereafter, adhesive may be applied to the riffled orcorrugated surface, before the sheet meets the main production line 1605and engages the now SAP-lined first sheet 1625. At this juncture, athree-layered composite is formed and advanced on the production line.In the embodiment shown, the composite is passed between a pair ofembossing rollers 1660 to apply a desired bonding pattern on thecomposite and form pockets of SAP aggregates. The resultant absorbentcomposite may, therefore, feature a plurality of spaced-apart pocketshaving a top and bottom elongatable substrates. The pockets in thecentral region may fuller and contain more SAP than pockets located tothe side of the central region.

FIG. 17 illustrates a further variation of the system and methodillustrated by FIG. 16 (wherein like reference numerals are used toindicate like elements). Like the absorbent composite described inrespect to FIG. 16, the absorbent composite made by this system 1700 andprocess provides a plurality of pockets of SAP aggregate having anelongatable top layer and an elongatable bottom layer. The absorbentcomposite employs, however, a third or intermediate layer that is notelongatable. The intermediate layer may be provided by tissue material,which is considered breakable when wetted. Such an absorbent compositeconstructions is illustrated by FIG. 3C. As shown in FIG. 18, a thirdsubstrate 1765 is applied intermediate the two sheet 1725, 1735 and morespecifically over the SAP-lined first sheet. SAP is then deposited onthe non-corrugated surface of the intermediate sheet 1765 before thethird sheet 1755 is applied over the then SAP-lined intermediate sheet1765. After engaging embossing rollers 1760 for bonding, the resultantabsorbent composite features a plurality of spaced apart pockets of SAPaggregate, wherein the three-layered pocket is made expandable top andbottom nonwoven substrates.

It is noted that in the various exemplary descriptions provide above,there are occasional mention of a corresponding steps or processes inmaking the core composite (or disposable absorbent article). Althoughthe description may not necessarily be provided from the perspective ofmanufacturing product, it is believed that various manufacturing or corepreparation methodologies, and equipment associated therewith, willbecome apparent from a reading of the various descriptions, perhaps inconjunction with common knowledge in the art or the references citedherewith.

The foregoing description has been presented for purposes ofillustration and description of preferred embodiments. This descriptionis not intended to limit associated concepts to the various systems,apparatus, structures, and methods specifically described herein. Forexample, the various pocket designs may be employed in various types ofdisposable absorbent articles. Moreover, the various mechanisms ofincreasing void space or volume may be used in different combination,and at varying degrees, as required for the absorbency demands of aproduct. The embodiments described and illustrated herein are furtherintended to explain the best and preferred modes for practicing thesystem and methods, and to enable others skilled in the art to utilizesame and other embodiments and with various modifications required bythe particular applications or uses of the present invention.

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 26. An absorbent core composite for incorporation into adisposable absorbent article, the absorbent core composite comprising: afirst material layer having an outside surface forming a bodyside outersurface of the absorbent core composite; a second material layer havingan outside surface forming an opposite outer surface of said absorbentcore composite; and a first layer of absorbent particles disposedbetween said outer surfaces of the absorbent composite and having anaverage size dimension; a second layer of absorbent particles disposedbetween said outer surfaces of the absorbent composite, said absorbentparticles of said second layer having an average size dimension lessthan the average size dimension of the first layer; and wherein saidfirst layer of particles are situated substantially in the firstmaterial layer and the second layer of particles are situatedsubstantially in the second material layer.
 27. The absorbent compositeof claim 26, wherein said average size dimension of particles of thefirst layer is greater than 300 microns and said average size dimensionof particles of the second layer is 0-300 microns.
 28. The absorbentcomposite of claim 26, wherein said first material layer is a lowdensity nonwoven and said second material layer is a nonwoven having ahigher density than the low density nonwoven.
 29. The absorbentcomposite of claim 26, further comprising an intermediate layer ofabsorbent particles situated between said first and second layer ofabsorbent particles, wherein said absorbent particles are SAP particles.30. The absorbent composite of claim 29, wherein an average sizedimension of SAP particles, in microns, in each of the first, second,and intermediate layer of particles are 0-300, 300-600, and 600-850,respectively.
 31. The absorbent composite of claim 30, wherein saidfirst, intermediate, and second materials layers have a density of 0.01to 0.03 g/cc, 0.03 to 0.08 g/cc, and 0.09 to 0.12 g/cc, respectively.32. (canceled)
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 42. An absorbent core composite for incorporation into adisposable absorbent article, the absorbent core composite comprising: abodyside first material layer; and a second material layer; and whereinsaid first and second material layers define a space therebetween, saidspace containing superabsorbent particles; and wherein said layer ofabsorbent particles includes a population of SAP particles and apopulation of non-SAP spacing particles that are smaller than said SAPparticles and generally positioned between two or more SAP particles,thereby spacing said two or more SAP particles from one another.
 43. Theabsorbent composite of claim 43, wherein said spacing particles areselected from the group of spacing particles consisting of: inertparticles; water-soluble particles; volatile particles; ion-exchangeparticles; and combinations thereof.
 44. The absorbent composite ofclaim 43, wherein said layer of absorbent particles further includehotmelt binder particles
 45. The absorbent composite of claim 44,wherein a ratio SAP particles to and said hotmelt binder particles isabout 1:1.
 46. The absorbent composite of claim 45, wherein said hotmeltbinder particle is a water sensitive hotmelt particle.
 47. The absorbentcomposite of claim 43, wherein the absorbent particles is a combinationof SAP particles selected from the group of SAP particles consisting of:spherical SAP; flake form SAP; and superabsorbent fiber SAP.
 48. Theabsorbent composite of claim 42, wherein said spacing particles arehotmelt particles that melt upon application of heat.
 49. A disposableabsorbent article, comprising: a chassis body defined by a first endmargin and a second end margin longitudinally spaced from the first endmargin, the end margins partially defining front and back waist regionsthat are positioned about a wait of a user during wear of the absorbentarticle; a topsheet; a backsheet; and an absorbent composite disposedbetween the topsheet and backsheet, the absorbent composite including, afirst material layer having an outside surface; a second material layerhaving an outside surface; and a first layer of absorbent particlesprovided between said outside surfaces, a second layer of absorbentparticles provided between said outside surfaces, said second layer ofabsorbent particles having absorbent properties different from saidfirst layer.
 50. The disposable absorbent article of claim 48, whereinsaid second layer of absorbent particles is situated in said secondmaterial layers, said absorbent particles of said second material beinggenerally smaller than absorbent particles of said first layer, andwherein said second material layer is positioned beneath the firstmaterial layer and has a lower density than the first material layer,said absorbent composite further comprising an intermediate materiallayer situated between said first and second material layers and havinga density intermediate that of the first and second material layers. 51.The disposable absorbent article of claim 50, wherein said absorbentparticles are SAP particles, said first and second material layers beingbonded at a plurality of bond sites to define a plurality of pocketseach containing said SAP particles.
 52. The disposable absorbent articleof claim 49, wherein said absorbent particles are SAP particles, saidfirst layer being laterally spaced from the second layer by alongitudinally extending SAP-free zone.
 53. The disposable absorbentarticle of claim 49, wherein said layer of absorbent particles isdivided into two outer zones and a central zone therebetween, saidcentral zone having a SAP composition different from SAP compositions ineach of the outer zones and effecting an absorption property differentfrom absorption properties of each of the outer zones.
 54. Thedisposable absorbent article of claim 53, wherein said SAP compositionof said central zone is characterized as slow absorbing with highabsorption underload and high permeability, and said SAP composition ofsaid outside zones is characterized as slow absorbing with lowabsorption underload and low permeability.
 55. The disposable absorbentarticle of claim 53, wherein said outside zones includes a mixture ofSAP particles and ion-exchange materials.
 56. The disposable absorbentarticle of claim 49, wherein said first layer of absorbent particles,said second layer of absorbent particles, and said first and secondmaterial layers together form an absorbent body, said absorbent bodybeing folded such that said first layer of absorbent particles is foldedonto the second layer of absorbent particles.
 57. The disposableabsorbent article of claim 55, wherein said absorbent body is foldedalong two fold lines such that two flaps come together to form the firstlayer of absorbent particles adjacent the second layer of absorbentparticles.
 58. The disposable absorbent article of claim 56, whereinsaid first and second material layers are bonded at a plurality of bondsites to define a plurality of spaced apart pockets each containing SAPaggregates.
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